Fixing some basic coding style stuff
Fixed the base tabbing
One more code style fix
Rewrote the main Navception code to run on the wp_get_nav_menu_items hook.

This rewrite allows the navcepted items to be added to the menu items before
the nav menu walker is used, making a few filters no longer needed.
Organized the actions/filters
Removed an unused private variable
Declaring functions as public and private, adding a nice newline at the end of file
Updated the add_nav_box() function to not need to include the nav-menu.php file.

The issue was that the 'nav_menu_meta_box_object' filter had a function added to it before
the 'admin_init' action, which is earlier than the wp-admin/includes/nav-menu.php file
is loaded. So applying that filter would cause WP to fall on its face, because it's trying to
run a function that hasn't been loaded up yet.
So just use my new custom filter, or just don't care about it: 'navception_nav_menu_meta_box_object'
Organized the functions in a way that doesn't annoy me
Document all the things!
Renamed the nav_id_prefix variable and added a comment
refactored add_nav_box() to return early rather than tab
Forgot to negate a check for the last commit >_<
Refactored the enqueue script function to have less tabbing
Accidentally made warn_of_limbo() private when it needs to be public >_<
Renamed pw_load_scripts, because I'm pretty sure I copied that from stackoverflow
Refactored check_for_limbo() to reduce tabbing.
Updated the plugin to be a singleton, because why not
Added the version number to the class and added that number to the wp_enqueue_script call
Updated the version number to 2.0.0